When using a lighting device to illuminate an area it is often found necessary to alter the beam of the projected light to provide control over the color or focus. For example often a flashlight might be equipped with a means for changing the profile of the emitted light beam from a spot to a wash.
U.S. Pat. No. 4,855,884 to Richardson discloses a variable beam width stage light with a single light source, relying on an axially movable reflector for changes in beam width. The reflector is constructed of a plurality of reflective leaves that are moved by a motor to change the focal length of the reflector. U.S. Pat. No. 4,729,070 to Chiu discloses an adjustable ring for concentrating multiple beams of light. Chiu discloses an apparatus for changing the angle of incidence of a plurality of light sources arranged in a ring. A threaded holder surrounds the ring of light sources while a cam mechanism adjusts the angle of the light sources that is operated by turning the threaded holder. U.S. Pat. No. 5,752,766 to Bailey et al. discloses a multi-color focusable LED stage light. A linear actuator is operable to move a base member containing an array of LEDs which in turn cause the LED array to change the direction of the optical axes of a substantial number of LEDs. By deforming the base member 20 in Bailey, the LEDs can be converged or diverged on an area to be illuminated.
Multi-parameter lights of the prior art utilize a single light source with mechanisms driven by motors to vary the focus, color, position and intensity. U.S. Pat. No. 3,845,351 to Ballmoos et al. titled: “METHOD AND APPARATUS FOR THE ADJUSTMENT OF A PLURALITY OF FLOODLIGHTS” discloses a number of floodlights especially for the illumination of a stage or studio, in which the parameters azimuth, elevation, brightness, focus and color of a bundle of light rays of each floodlight are adjusted to an optimum value for any one of a plurality of lighting effects.
U.S. Pat. No. 4,392,187 to Bornhorst titled: “Computer controlled lighting system having automatically variable position, color, intensity and beam divergence” illustrates another example of the prior art. Each of the instruments houses a central lamp and an optical system designed to collimate the light from the lamp and vary the parameters of the light by inserting motor driven optical components into the light by remote control.
Multi-parameter lights are generally controlled by a central control system via a serial data communications system. An operator operating the central control system may control each multi-parameter light separately to adjust the parameters. Each multi-parameter light may be provided with a communications address so that each multi-parameter light may be addressed separately by an operator operating the control system.
Multi-parameter lights of the prior art are depicted in a HIGH END SYSTEMS (trademarked) Product Line 1997 brochure. It is known in the art to construct a lighting device using a plurality of light emitting diodes (LEDs) such as disclosed in U.S. Pat. No. 5,752,766 to Bailey et al.
U.S. Pat. No. 5,652,766 to Bailey et al. titled “Multi-color focusable stage light” and is incorporated by reference herein describes an LED stage lighting instrument constructed of arrays of red, blue, and green LEDs.
The red, blue and green LEDs are operated in an additive color system to produce various colors of light by mixing the primary colors of red, blue and green together in various combinations. In my pending application entitled “IMPROVEMENTS TO LIGHTING DEVICES USING A PLURALITY OF LIGHT SOURCES”, filed on Mar. 15, 2000, Ser. No. 09/526,599 describe some of the disadvantages of constructing a lighting device using discrete spectral LEDs of Red, Blue and Green. When creating white light through the use of an additive color system using red, green and blue wavelengths (RGB), the spectral energy adjacent to the red, green and blue wavelengths is usually omitted. An RBG system used to create white light can sometimes be problematic when illuminating objects that absorb or reflect very specific wavelengths of light. Illuminating these types of objects with RGB derived white light often may result in an erroneous perception of color by the viewer as compared to viewing the object under continuous spectrum white light.
Broad-spectrum visible white light emitting diodes such as those manufactured by Nichia Chemical Corporation of Japan can be used to produce a lighting device that produces white light without using the discrete spectral LED's used in a color additive system. The term “white light LED” refers to a light emitting diode that provides a spectrum that is seen by the human eye for all purposes as white. One disadvantage is that the device constructed of exclusively white light LED's cannot produce colors without placing a color filter in the path of the projected light. Placing a single filter over a plurality of white light LED's can be accomplished but as the array of white light LEDs increases in numbers the filters become quite large.
U.S. Pat. No. 5,652,766 to Bailey discusses the use of a flexible base member to change the focus of a plurality of red, blue and green LEDs with an LED stage light. My co pending application, Ser. No. 09/526,599 discussed the use of a variable filter that may be a liquid crystal emulsion filter mounted after the light sources. Changing the voltage to the filter causes the light from the light sources to pass through the filter deflected or undeflected depending on the voltage state. The above methods alter the projected light from a narrowed angle to a wider angle by varying the diffusion of the light or by redirecting the individual light sources to a different emitting angle.